Brake mechanism



Feb; 21, 1933. s. SCHNELL 1,898,022

BRAKE MECHANISM Filed June 1, 1931 2 Sheets-Sheet l Inventor CHNELL Att'y.

Feb, 21 1933. s. SCHNELL 1,898,022

BRAKE MECHANISM Filed June 1, 1931 2 Sheets-Sheet 2 Inventar I s SCHNELL Patented Feb. 21, 1933 UNITED srA rEs ,PATENT OFFICE STEVE SCHNELL, O1 ST. LOUIS, MISSOURI, ASSIGNOB TO WAGNER. ELECTRIC CORPORA- 1310], S1. LOUIS, IISSOUBI, A CORPORATION OF DELAWARE BRAKE MECHANISM:

Application. filed June 1; 1931.- Serial No. 541,355.

My invention relates to braking apparatus and particularly to expanding brakes of the type em loying auxiliary means spaced from t a bra e actuating device to produce a radial pressure on the shoe to augment its pressure on the drum.

In internal expanding brakes comprising a'shoe of the circular band type, which is applied to the brake drum by expanding the adjacent free ends by some suitable means, the braking effect may be substantially increased by applying radial pressure to the band at a point intermediate its ends. This also-results in more uniform wear of the brake lining and consequently decrease in cost of maintenance. p

One prior method of applying-radial pressure to the brake band com rises the use of coo rating inclined lanes xed to'theband an to the backing p ate at ro er intervals about the circumference o t e drum to radially force the intermediate part of the hand into engagement with the drum upon -circumferential movement of the band with fixed inclined surface on the backing plate,

and there is present a high 'coeflicient. of friction, depen in upon the type of surface used and, as the s 0e is forced between the fixed inclined surface and thedrum by the circumferential movement of .the shoe with the drum, there results a wedgin effect. As

therslope of the inclined sur aces is -de-;:

creased,--that is, the angle between theinclined surfaces and a tangent-drawn to-the circumference of the drum where the projections of the inclined surfaces intersect the drum, is increased, .the wedging'efiect increases until'a shoe will be' c ed to the drum (a very undesirable feature in brakes). The slope of the inclined surfaces, therefore, determines the safe radial force that can be applied to the shoe b this type of pressure producing means. his safe radial force is not as large'as is desired in this type of brake and, therefore, it is an important int reached where the object of my invention to construct an auxiliary device of the inclined surface type that will produce a greater radial force against the shoe and at the same time elimitional view on the line 22 of Figure 1;

Figure 3 is a cross sectional view on the line 3-3 of Fi re 1; Figure 4 is a front view of a modi cation; and Fi e 5 is a front view of still. another modi cation (showing onllyethe lower part of the brake).

ferring to Figures 1 2, and 3 of the drawings, 1 indicates a rake drum, and

enclosing the open side of the drum is a backing late 2 secured by suitable means to the axl e housing or some fixed part of the vehicle. Mounted within the drum is a circular metal expansible brake band 3 carrying a suitable lining 4. A fluid cylinder 5 having the usual actuating pistons 1s mounted between the adjacent ends of the band for expanding it against thedrum. Asufvficiently strong spring 6 is also connected to the ends of the band to retract the band from the drum when the pressure on the actuating pistons has been relieved.

Mounted by means of rivets on the backing plate 2 adjacent the central art of the band and spaced from the bac 'ng late by spacers 7 is a fixed member 8 his fixed member has cut therein, on the edge adjacent the band two oppositel inclined surfaces 9 and 10 divej'lging towar the drum to form an inverted -shaped recess. Riveted to the web 11 of the brake is a pair of plates 12 and 13, one on each side of the web, and each havin opposed inclined surfaces 14 and 15 in t e inwardly extending edge which diverge toward the center of the drum to forma V-shaped recess. The

,fixed member 8 is so spaced from the backing plate that it lies between the two plates 12 and 13 fixed to the web of the band with the open end of its V-shaped recess overlapping the open end of the V-shaped recess in the plates 12 and 13. Mounted in the space formed by the sides of the V-shaped recesses is a floating roller 16 having enlarged ends 17 and 18. The enlarged ends of the roller are adapted to be in rolling contact ,with the V-shaped recesses of the plates 12 and 13'and the central part of the roller is adapted to be in rolling contact with the V-shaped recess in the plate 8, and since it projects between the enlarged ends of the roller, this plate maintains the roller in; operative position by preventing its axial movement.

An eccentric stop member 19 (see Figure 3), comprising a bolt 20, spring 21, and head 20 is mounted on the backing plate 2 adjacent the roller for adjusting the off osition of the brake band with respect to t e drum. Springs 22 and 23 hold the band a ainst the stop 19 when the brake is not app ied, and spring 22 is preferably s0 positioned that its pull on the band has a circumferential component whereby, in ofi position of the brakes, the roller is held in contact with opposing walls of the recesses Spaced approximately 120 degrees on each side of the eccentric stop 19 is a pair of similar stops 24 and 25 for determining the ofi position of the ends of the band. The three stops 19, 24 and 25, being spaced as shown, constitute a very convenient means for insuring equal clearance of the brake lining from the drum throughout its entire circumference when in its released positlon.

In the operation of the brake, when the ends. of the band 3 are expanded into engagement with the drum 1 by means of the cylinder pistons, the band tends to travel with the drum and if the drum is rotating in the direction of the arrow (Figure 1) the band will also be carried in the same direction. This causes the inclined surface 15 of the left hand sides of the recesses in plates 12 and 13, to be forced against the .roller 16 and the roller in turn to be forced a ainst the fixed inclined surface 9 on the right hand side of the recess in plate 8 and thus the band is forced into frictional engagement with the drum against the tension of spring 23. The greater the circumferential drag on the band the greater the'radial force exerted upon the band by the cooperatmg inclined surfaces and the roller means. The amount of radial force exerted on the band can be varied by changing the angle of the inclined surfaces 15 and 9 but regardless of the angle, within any desired that a convenient angle for the inclined. surfaces is approximately 30 degrees with respect to a drum .radius passing through the roller. 7

The operation of the brake, when the drum is rotatin in the opposite direction, is the same as a ove described except that the inclined surfaces 10 and 14 now cooperate with the roller to force the band against the drum. p I

In the modification shown in Fi re 4, there is disclosed an auxiliary radia force producing device for the band when it is carried with the drum in one direction and a radially extending anchor surface for the band when it is carried with the drum in the other direction. The structure is very similar to thatshown in Figure 1 with the exception that one side ,of the recesses in.the plates 8, 12 and 13 is approximately parallel to a drum radius passing through the center of the roller 16, as clearly'shown at 10' and 14. When the drum is rotating inthe direcward motlon of the vehicle) and the band is actuated to apply the brake, the surface 14' will move the roller 16 against the surface 10 on the fixed plate 8 as the band is car ried with the drum and no radial force will be applied by these parts. By locating the anchor device somewhat to the right of the center of the band, as shown in Figure 4, the wrappi'ngeflect is increased in the manner well understood and it is a matter of choice, from the standpoint of braking effect desired, at what point intermediate the ends of the brake band any of the anchoring devices herein shown, are located.

A spring 26 is fixed to the band and the backing plate 2 to assist in releasing the band from the drum upon release of the actuator and to at all times keep the inclined surfaces in contact with the interposed floating roller whereby there will be no lost motion nor conse uent noise resulting from engagement of the parts when the brake is applied. The stops 19, 24 and 25 are equally spaced about the circumference of the band in a similar manner as described with respect to Figure 1.

on each side of the central part of the brake band. In this figure the plate 27 is spaced from the backing plate in a similar manner as the plate of Figure 1 and has the inclined surface 10 formed in the edge thereof and a pair of plates 29 having inclined surfaces 14, parallelwith the inclined surface 10, are fixed to the band web 11. The roller is placed between theinclined surfaces and lt'and is in rolling contact therewith. The other anchoring device is similar, the inclined surface 9 of the fixed plate 28 being parallel with the inclined surfaces on the plates 30 fixed to the band and the roller 16 in rolling contact with the inclined surfaces. Springs 22 and 23 retract the band from the drum when the actuator is released. It is to be noted that this modification does not have the radial surfaces 10' and 14 shown in Figure 4 and, therefore, the band has a tendency to be carried with the drum in both directions of rotation of the drum when the brake is applied. This allows the inclined surfaces 9 and 15 and the roller 16 to force the hand against the drum in one direction of rotation and the inclined surfaces 10 and 14 to force the band against the drum in the other direction of rotation. The stops 19,

24 and 25 are preferably equally spaced about the band 1n the same manner as in Figure 4.

As indicated in Figures 1 and 2, I prefer to provide the shoe plates 12 and 13 with extensions 31 which project into slots formed in the shoe flange to receive the circumferential thrust of the shoeand thus avoid the necessity of applying suflicient rivets for this purpose.

2. In braking ap aratus, the combination of a brake drum, a rake shoe adapted to'cooperate therewith, an anchorage for the shoe having a stationary inclined surface,

I means on the shoe forming a second inclined surface, and a member interposed tween and in rolling contact with each of said surfaces, whereby radial pressure is applied to. the shoe in response to. circumferent1al mo've-" ment of the shoe.

3. A brake comprising a friction device 7 and an adjacent stationary support, anchor means for said friction device including an inclined surface on the friction device and a member on the support having an inclined surface, and a floating roller interposed between'and contacting with the two inclined surfaces.

4. In braking apparatus, the combination of a support, a brake drum, a friction member carried by the support and adapted to cooperate with the drum, means to actuate said friction member into engagement with the drum, said friction member being adapted to have a slight rota-tive movement with the drum, said friction member being provided with an inclined surface spaced from the actuating means, an anchor member carried by the support and provided with a surface inclined in the same direction as said inclined surface on the friction member, and a floating roller interposed between said surfaces.

for limiting the movement of the friction element with the rotatable member and for forcing said element intoengag'ement with the rotatable member, said anchor means com rising a member having an inclined sur ace and secured to the friction element, a second member having an inclined surface parallel with the first named inclined surface and secured to the support, a floating member interposed between and in rolling contact with the ,surfaces, and means for holding the floating member in contact with the inclined surfaces when the friction eleof surfaces diverging away from the adja-- cent portion of the rotatable member, an anchorage for said friction element comprising a fixed member-having a pair of abutment surfaces diverging toward the said to tatablc member and radially aligned with the first mentioned pair of diverging surfaces, and a floating element cooperating with both pairs of surfaces to limit movement of the friction elementwith the drum.

8. In. braking apparatus, the combination 0 7' a rotatable drum, a-friction member adapted to cooperate withthe drum and having a slight circumferential movement with the drum when in engagement there with, said member being provided with a V-shaped recess, anchor means for the friction element intermediate'its ends and comprising a fixed abutment member provided with a V-shaped recess adjacent the first named recess, and a floating roller cooperating withthe sides of both recesses.

9. In braking apparatus, the combinatio of a fixed support, a rotatable member, a

friction element adapted to cooperate with said member, means on said frictlon element forming an abutment surface, an anchor member secured to said support and having an abutment surface-thereon adjacent the first named surface, a roller interposed between said surfaces, and means for holding the roller in contact with said surfaces when the friction element is in off position. a

10. In braking apparatus, the combination of a rotatable member, a friction element adapted to cooperate with said member, and means for applying radial pressure to the friction element intermediate the ends-thereof, said means comprising elements having inclined surfaces and a roller in rolling contact w1th said incllned surfaces, said roller having enlarged ends cooperating with one of said elements to retain the roller in position.

11. In braking apparatus, the combination of a support, .a rotatable member, an expansible friction element adapted to cooperate therewith, means, including a roller,

intermediate the ends of said expansible friction element for applying radial pressure to said element when the rotatable member is rotating in one direction, and means cooperating with the roller-for preventing circumferential movement of the friction element 49 with the rotatable member when the mem- "beris rotating in the opposite direction.

12. In braking apparatus, the combination of a rotatable drum, an expansible brake shoe adapted to cooperate with the drum, an abutment member having inclined surfaces diverging toward the drum periphery,a pair of members fixed to the shoe and having inclined surfaces diverging toward the center of the drum, and a floating roller,

' said roller having enlarged ends cooperating tion of a support, a rotatable drum, an ex-' pansible brake band adapted to cooperate w1ththe drum, said band having slight circumferential movement with the drum when U in engagement therewith, a pair of spaced apart auxiliary applying devices for radially forcing the band" into engagement with the drum, one being operative in one direction of rotationof the drum and the other operative in the other direction of rotation of the drum, each device comprising a member fixed to the support and having an inclined surface thereon and a second member fixed to the band and having an inclined surface spaced from the inclined surface on the fixed member, each auxiliary applying device also comprising a floating roller interposed between and in rolling contact with the said inclined surfaces. I

14. An auxiliary applyingdevice for an expansible brake shoe comprising a pair of parallel members fixed to the shoe and each provided with an inclined surface, a fixed member interposed between the members fixed to the shoe and provided with an inclined surface adjacent the first named inclined surfaces, and a floating element in rolling contact with all of said inclined surfaces. y

15. In braking apparatus, the combination of a rotatable element, an expansible brake shoe adapted to cooperate with said element, a pair of members fixed to. the brake shoe and each provided with a. V- shaped recess therein, a fixed member having a V-shaped recess therein and interposed between the pair of members fixed to the shoe and a floating roller, said roller having enlarged ends cooperating with the sides of .the V-shaped recesses of the members fixed to the brake shoe, and the central part cooperating with the sides of the V-shaped recess of the fixed member.

16. An auxiliary applying device for an expansible brake shoe, comprising a pair of parallel members carried by the shoe and each having inclined surfaces, a fixed member interposed between the members fixed to the shoe and provided with inclined surfaces, and a floating roller, the ends of the roller havinga greater circumference than the central part, said ends cooperating with the inclined surfaces on the membersfixe'd to the shoe and the central part cooperating with the inclined surfaces on the fixed member, said fixed member also cooperating with theends of the roller to prevent axial movement of the roller, and spring means for maintaining contact between theowalls and the inclined surfaces when the'brake shoe is in off position.

17. In breaking apparatus, the combination of a support, a rotatable drum, a brake shoe adapted to cooperate therewith, said shoe having slight rotative; movement with the drum when in engagement therewith, a member fixed to the support and provided with a recess therein, one side of said recess being substantially parallel to a drum radius and the other side of the recess being inclined thereto, .a member fixed to the shoe and having a recess therein similar to the first mentioned recess with its inclined side inclined in the same direction as the inclined side of the fixed member and spaced therefrom, and a floating member in rolling contact with the sides of the recesses.

18. In braln'ng apparatus, the combination of a support, a brake drum, a friction member carried by the support and adapted to cooperate with the drum, the friction member being adapted to have a slight rotative movement with the drum when applied thereto, said friction member being pro- 30 vided with an inclined surface, an anchor member carried .by the support and provided with an inclined surface parallel with the inclined surface of the friction member and a floating roller interposed between said 35 surfaces and in rolling contact therewith whereby when the friction member is applied to the drum the rotative movement of the friction member with the drum will cause the inclined surface on the friction I 0 member to move relatively to and parallel 'with the inclined surface on the anchor member and force the friction member into tighter engagement with the drum.

19. In braking apparatus, the combination of a support, a brake drum, a brake band carried by the support and adapted to engage the major portion of the circumference of the drum, means between the ends of the band for expanding the band into engagement with the drum, the band being adapted to have a slight rotative movement with the drum when applied thereto, said band being provided with an inclined surface intermediate. its ends, an anchor member on the support and provided with an inclined surface adjacent the first named inclined surface, and a floating roller interposed between said surfaces and in rolling contact therewith.

{ In testimony whereof, I hereunto afiix my signature, this 22nd day of May, 1931.

STEVE SCHNELL. 

